The official Twitter account of The Misfit of the Demon King Academy shared a message recently. The message reads :

Did you think The Misfit of the Demon King Academy was over? You should wait a little longer.

「これで『魔王学院の不適合者』が最後と思ったか？
もうしばらくだけ、待っているがよい」#魔王学院 pic.twitter.com/nhUGgxFa4E

— TVアニメ「魔王学院の不適合者　～史上最強の魔王の始祖、転生して子孫たちの学校へ通う～」 (@maohgakuin) February 24, 2021

A short preview of the song ‘Dear Descendants’ is also available. It is also a part of the 6th Blu-ray DVD volume.

【親愛なる子孫達へ】
アノスのスペシャルキャラクターソングPVを公開！

「Dear Descendants」
作詞・作曲・編曲：コヤマヒデカズ(#CIVILIAN)
唄：アノス・ヴォルディゴード(CV：#鈴木達央)

楽曲のフルver.はBlu-ray&DVD第6巻に限定収録！

▼高画質版はコチラhttps://t.co/mg6XiCe4fm#魔王学院 pic.twitter.com/lgGjCd63v3

— TVアニメ「魔王学院の不適合者　～史上最強の魔王の始祖、転生して子孫たちの学校へ通う～」 (@maohgakuin) February 24, 2021

Crunchyroll describes the anime as:

Anos Voldigord was a tyrannical Demon King that eradicated humans, spirits, and even the gods. But he became bored of eternal warfare and reincarnated with dreams of a peaceful world. However, what awaited him in reincarnation after 2000 years were descendants who became too weak after being accustomed to peace, and all sorts of magic that deteriorated to the extreme. Anos enters Demon King Academy that gathers and educates those who are viewed as the reincarnation of the Demon King. But the academy could not see through his true powers and ends up branding him as a misfit! 

Source : The Misfit of the Demon King academy official Twitter account.